Artificial skin can feel touch; robots prepare to out-human humans

Researchers have found plenty of uses for carbon nanotubes, but a team at Stanford's of the Bao Research Group found a new use for them: artificial skin. The researchers created a stretchable, transparent skin-like sensor that not only is elastic like skin, but can also sense touch and pressure like the real thing.

To create this wonder-sensor skin, the researchers began by spraying carbon nanotubes in a liquid suspension onto a thin layer of silicone. The material was then stretched repeatedly to align and pull the bundles of sprayed on nanotubes across the entire surface. The nanotubes formed into springs, called "nano-springs" by the researchers, as a result of the stretching, which allows the artificial skin to be pulled and squeezed without any permanent deformation.

The actual sensor consists of two of these stretchable nano-spring layers oriented so that the capacitive carbon coatings are facing each other with a layer of easily deformed type of silicone between them. An electrical charge is put into the middle silicon layer so that it acts like a battery with a positive and negative side.

When the sensor is pressed, it alters the amount of charge the silicon can hold, and the nano-springs detect this change, which is translated into "feeling".

"This sensor can register pressure ranging from a firm pinch between your thumb and forefinger to twice the pressure exerted by an elephant standing on one foot," Darren Lipomi, a postdoctoral researcher in Bao's lab, said in the press release.

The sensor can even determine what kind of pressure is being place on it. Single point compression shows up as a bulls-eye pattern while pinching it reveals the greatest amount of deformation as line.

The Bao Research Lab previously created a sensor so sensitive to pressure that it could detect the weight of 20-milligram bluebottle fly and with a little modification to surface of the electrode; its new sensor could do the same. The applications of this touch sensitive artificial skin could go to your next touchscreen, layered onto prosthetics, or even create the first feeling robot.

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